1. Field of the Invention
The present invention relates to a tape bonding apparatus and more particularly to a cooling system for cooling upper and lower clampers used in the tape bonding apparatus.
2. Prior Art
Tape bonding apparatuses for bonding a plurality of leads installed at fixed intervals on a tab tape to bumps of semiconductor pellets or single bump units are disclosed in, for example, Japanese Patent Application Publication (Kokoku) Nos. 2-3543 and 4-58183 and Japanese Patent Application Laid-Open (Kokai) No. 2-273950. FIG. 5 shows an essential portion of the typical tab tape bonding apparatuses.
In this bonding apparatus, a tab tape 2 on which a plurality of leads 1 are installed as shown in FIG. 6 is fed along an upper clamper 3 which is installed in the bonding position. When the leads 1 on the tab tape 2 are positioned in the bonding position, a lower clamper 4 is raised so as to press the tab tape 2 against the upper clamper 3. In this state, the positions of the leads 1 on the tab tape 2 are detected by a camera (not shown). Meanwhile, a semiconductor pellet 6 which has bumps 5 is carried on a pellet stage 7, and the positions of the bumps 5 of the semiconductor pellet 6 are detected at the same time as the positions of the leads 1 by the camera (not shown) that detects the positions of the leads 1 or are detected beforehand by a separately installed camera.
If there is a positional discrepancy between the leads 1 and bumps 5, the tab tape 2 and semiconductor pellet 6 are moved relative to each other so that the leads 1 and bumps 5 are aligned. Then, the leads 1 on the tab tape 2 are pushed downward, pressed against the bumps 5 and then bonded by a bonding tool 8.
In the tape bonding apparatus as described above, the pellet stage 7 and the bonding tool 8 are heated by heaters in order to improve the bonding conditions between the leads 1 and bumps 5 (although this is not disclosed in the patents listed above).
As described above, the leads 1 and bumps 5 are bonded after the positions of these have been confirmed by a camera. However, since the pellet stage 7 and the bonding tool 8 are heated, the upper clamper 3 and lower clamper 4 are also heated by radiant heat from the pellet stage 7 and the bonding tool 8; and when the upper clamper 3 and lower clamper 4 reach a certain temperature, heat is transmitted to the leads 1, and the leads 1 undergo thermal expansion. However, since the bonding between the leads 1 and bumps 5 is performed after the positions of these have been confirmed by the camera and after any positional discrepancies have been corrected in accordance with the detection results, the alignment of the leads 1 and bumps 5 at the time of bonding tends to become different from the alignment at the time of positional confirmation by the camera; thus hindering a high-precision bonding. In particular, since there has recently been a trend toward narrower lead widths and thinner lead thicknesses as a result of increasingly fine lead pitches on tab tapes, the thermal deformation of the leads has become a major problem.